This invention relates generally to centrifugal separators. More particularly, the present invention relates to a new and improved centrifugal separator for separating a liquid material from a particulate material.
As shown in the Derton et al U.S. Pat. No. 4,135,659, issued Jan. 23, 1979, centrifugal separators of the horizontal type have been provided for handling slurries of metal chips, metal turnings, or other particulate matter obtained from milling operations. Centrifugal force generated by rotating the separator bowl throws the slurry against the side of the bowl and moves it towards the rim. The rim area is provided with a screen comprised of a series of axially parallel rods forming a slotted surface through which the liquid is discharged under the influence of the centrifugal force. This drainage screen may be permanently mounted to the bowl or may be attached in a manner which allows removal and reinstallation of different drainage screens. The discharged liquid is collected in a chamber which surrounds the drainage screen while the particulate matter glides axially along the rods and is discharged over the rim of the bowl.
The drainage screen of such a bowl is of fixed axial length. However, it has been shown that the performance of the separator is affected by the characteristics of the slurry and that a particular drainage screen surface area may or may not perform adequately for a given slurry. For example, different solid materials, different solid particle shapes, and slurries having different liquid/solid ratios behave differently as they pass over the drainage area.
In addition, the slurry liquid serves as a lubricant, facilitating movement of the solid materials. If all of the liquid is removed from the slurry prematurely, the solid materials may form a "beach", blinding the drainage area and impairing movement of the solid materials.
Separators which utilize removable drainage screens may allow the use of screens which have drainage characteristics customized to particular slurries. Typically, such separators require disassembly of the separator, removal of the installed drainage screen, installation of a drainage screen having a more appropriate surface area, and reassembly of the separator. Such operation is cumbersome and time consuming.